An airbag device arranged in front of a passenger's seat of a vehicle has an inflator that generates gas when impact is inputted, and a folded bag body, which are incorporated inside an instrument panel. A breakable deployment wall is provided in an upper part of the instrument panel, and the airbag device is arranged below the deployment wall. In the airbag device, when the inflator generates high-pressure gas at the time of input of impact, the bag body is inflated and deployed by the gas pressure, breaks the deployment wall, and bulges out toward the passenger's seat.
This type of airbag device is installed in a vehicle body with the inflator and bag body held in a metal retainer. The retainer has a bottom wall facing the deployment wall of the instrument panel, and side walls continuous with the bottom wall. Here, the folded bag body is stored inside a recess surrounded by the bottom wall and side walls, while the inflator is installed on the lower surface side of the bottom wall.
Various parts, such as an air-conditioner unit and electric parts, are arranged on the inner side of the instrument panel. Hence, lowering the height of the instrument panel, for example, would bring the inflator of the airbag device closer to the other parts inside the instrument panel. This sets a limitation on the height of the instrument panel and layout of parts inside the instrument panel.
As a countermeasure, airbag devices have been developed in which an inflator is installed on the front or rear, or right or left side wall of a retainer, instead of on the lower surface side of the bottom wall of the retainer, to keep the inflator from bulging out in the height direction (see Japanese Patent Application Publication No. 2012-111389, International Patent Application Publication No. 2010/150603, and International Patent Application Publication No. 2004/045920, for example).
However, when the inflator is installed on the side wall of the retainer, the inflator is arranged on the lateral side of a folded part of the bag body stored inside the recess of the retainer. This makes it difficult to efficiently deploy the bag body toward the deployment wall by high-pressure gas of the inflator when impact is inputted, and requires measures such as an increase in gas pressure of the inflator.